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A Magnetic Resonance Imaging (MRI) apparatus includes a static magnetic-field magnet that generates a static magnetic field in an imaging area in which a subject is to be placed; a main coil that is provided on the inner side of the static magnetic-field magnet, and applies a gradient magnetic field

A Magnetic Resonance Imaging (MRI) apparatus includes a static magnetic-field magnet that generates a static magnetic field in an imaging area in which a subject is to be placed; a main coil that is provided on the inner side of the static magnetic-field magnet, and applies a gradient magnetic field onto a subject placed in the static magnetic field; and a shield coil that is provided between the static magnetic-field magnet and the main coil, and shields a gradient magnetic field generated by the main coil. Moreover, a Radio Frequency (RF) coil side cooling system including a plurality of cooling pipes that circulates a coolant in pipe is provided on the inner side of the main coil.

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1. A magnetic resonance imaging apparatus comprising: a static magnetic-field magnet configured to generate a static magnetic field in an imaging area in which a subject is to be placed;a main coil that is provided on an inner side of the static magnetic-field magnet, and which is configured to appl

1. A magnetic resonance imaging apparatus comprising: a static magnetic-field magnet configured to generate a static magnetic field in an imaging area in which a subject is to be placed;a main coil that is provided on an inner side of the static magnetic-field magnet, and which is configured to apply a gradient magnetic field onto the subject when placed in the static magnetic field;a shield coil that is provided between the static magnetic-field magnet and the main coil, and which is configured to shield the gradient magnetic field generated by the main coil;a radio-frequency coil that is provided on an inner side of the main coil, and which is configured to apply a radio-frequency magnetic field onto the subject placed inside the static magnetic field;a radio-frequency shield that is provided between the main coil and the radio-frequency coil, and which is configured to shield the radio-frequency magnetic field generated by the radio-frequency coil; andan inner-layer cooling pipe that is provided on an inner side of the main coil and between the radio-frequency coil and the radio-frequency shield, and which is configured to pass a coolant in the inner-layer cooling pipe. 2. The magnetic resonance imaging apparatus according to claim 1, wherein the radio-frequency shield comprises an electrically conductive surface formed in a substantially drum shape, said shield being provided between the main coil and the radio-frequency coil, and including a slit that is formed at a position at which an eddy current would be produced by the main coil. 3. The magnetic resonance imaging apparatus according to claim 2, wherein an insulating film formed from an insulating material is provided between the inner-layer cooling pipe and the radio-frequency shield. 4. The magnetic resonance imaging apparatus according to claim 2, further comprising an outer-layer cooling pipe that is provided on an outer side of the main coil, and which is configured to pass a coolant in the inner-layer cooling pipe. 5. The magnetic resonance imaging apparatus according to claim 2, wherein: the inner-layer cooling pipe includes a plurality of cooling pipes arranged in parallel,the inner-layer cooling pipe further includes a branching pipe that branches a coolant supplied from a chiller, and flows branched coolant into each of the cooling pipes, andeach of the cooling pipes and the branching pipe included in the inner-layer cooling pipe are connected to each other via a pipe that is formed from an insulating material. 6. The magnetic resonance imaging apparatus according claim 2, wherein the inner-layer cooling pipe includes a first cooling pipe that passes a coolant in a first direction, and a second cooling pipe provided in parallel with the first cooling pipe, and the second cooling pipe passes a coolant in a second direction opposite to the first direction in which the first cooling pipe passes the coolant. 7. The magnetic resonance imaging apparatus according to claim 1, wherein an insulating film formed from an insulating material is provided between the inner-layer cooling pipe and the radio-frequency shield. 8. The magnetic resonance imaging apparatus according to claim 1, further comprising an outer-layer cooling pipe that is provided on an outer side of the main coil, and which is configured to pass a coolant in the inner-layer cooling pipe. 9. The magnetic resonance imaging apparatus according to claim 8, wherein the inner-layer cooling pipe is formed so as to have a pipe diameter smaller than a pipe diameter of the outer-layer cooling pipe. 10. The magnetic resonance imaging apparatus according to claim 8, wherein: the inner-layer cooling pipe and the outer-layer cooling pipe are each formed in a helical shape, andthe inner-layer cooling pipe is formed to have narrower intervals within its helical shape than the outer-layer cooling pipe. 11. The magnetic resonance imaging apparatus according to claim 8, wherein: the inner-layer cooling pipe and the outer-layer cooling pipe are each arranged in a helical shape, andthe inner-layer cooling pipe is formed so as to have a longer length in a direction along a helical axis than the outer-layer cooling pipe. 12. The magnetic resonance imaging apparatus according to claim 1, wherein: the inner-layer cooling pipe includes a plurality of cooling pipes arranged in parallel,the inner-layer cooling pipe further includes a branching pipe that branches a coolant supplied from a chiller, and flows branched coolant into each of the cooling pipes, andeach of the cooling pipes and the branching pipe included in the inner-layer cooling pipe are connected to each other via a pipe that is formed from an insulating material. 13. The magnetic resonance imaging apparatus according to claim 12, wherein a low dielectric substance is filled between each of the cooling pipes included in the inner-layer cooling pipe. 14. The magnetic resonance imaging apparatus according to claim 1, wherein the inner-layer cooling pipe includes a first cooling pipe that respectively; and a coolant in a first direction, and a second cooling pipe provided in parallel with the first cooling pipe, and the second cooling pipe respectively; and a coolant in a second direction opposite to the first direction in which the first cooling pipe respectively; and the coolant. 15. The magnetic resonance imaging apparatus according to claim 1, wherein the inner-layer cooling pipe covers an inner surface of the radio-frequency shield.